U.S. Pat. No. 4,558,181 describes a device which monitors several selected conditions at a local area. If the selected conditions exceed predetermined limits or deviate from normal in some other manner, the device places a telephone call to one of several preselected telephone numbers and waits for the preselected telephone to be answered. If an answer is received, the device gives a speech message describing its location and the alarm condition detected. If the preselected telephone is not answered, the device calls another preselected telephone number in its list of telephone numbers in an attempt to reach someone and report the alarm condition. The device is exceptionally versatile in the types of conditions which can be monitored and in the means of providing information to persons designated when alarm conditions exist. The device had only a single mode of communication; however, this is through synthetic speech.
The Invention
The present invention contemplates a portable monitoring device for monitoring conditions at a selected location and communicating an alarm when conditions deviate from preselected ranges. The present invention communicates its alarm over the existing telephone network in either a synthesized speech format or in a digital data representation format.
In accordance with one aspect of the present invention, there is provided a portable self-contained device for monitoring a selected local area having a standard telephone terminal connected to the commercial telephone network for the occurrences of any of a plurality of conditions adjacent the local area. These conditions can be high or low temperature, power interruption, operation of a smoke, fire or burgular alarm, existence of a high water level, entrance through a restricted area or virtually any other electrically monitorable condition. When one or more of the selected conditions deviate from preset ranges, an alarm signal is generated and the system of the present invention communicates such alarm signal to either a remote data reception terminal or a remote human being through transmission of an alarm signal in digital code or synthetic speech.
In accordance with the general scheme of the present invention, there is provided an electronic circuit and several sensors at the local area to be monitored. The sensors generate signals when the conditions being monitored vary from a preselected range or exceed certain limits. Analog processing circuits condition the signals from the sensors and supply appropriate signals to a microprocessor through an analog to digital converter. The microprocessor has associated with it random access memory (RAM) into which telephone numbers, identification codes and other data required for the operation of the circuit is loaded by means of a key pad. When the output of one of the sensors indicates that a preselected limit has been exceeded, an alarm condition is established and an alarm signal is generated. The alarm signal causes the circuit to generate telephone dialing signals initiating a telephone call on a standard telephone circuit interconnection. The system first attempts to reach the telephone number stored in its first preselected telephone number memory location. If an answer occurs at this location, the circuit looks for a digital acknowledgement signal or "handshake" informing the circuit that a digital terminal is connected at the number recalled. Once this handshake is received, the microprocessor applies digital signals to a modem which communicates with the terminal at the number called such that a code identifying the location being monitored and a message describing the alarm condition are sent to the terminal. If an answer from the first destination number is not received, the circuit continues to try this number until an answer is received or a predetermined period of time expires. After the expiration of this period of time, the circuit calls secondary preselected telephone numbers stored in its memory. A "speech" or "digital" designation signal is stored in association with each secondary preselected number. This designation signal tells the microprocessor the proper mode of communication for the number being called. An appropriate digital or speech format signal is generated and applied to a speech amplifier or a modem, and to the telephone lines informing the person or terminal at the preselected number of the alarm condition.
Further in accordance with the invention, means are provided for sensing the presence of a telephone call to the device and determining whether the call originating station is equipped to communicate in the digital format or should be addressed in speech. If the call originating station is digital capable, that is, the call originated from a computer-like terminal or teletype-like terminal, status information is given in digital machine readable form in one of two modes. First, if the digital inquirer so requests, the device disconnects from the call and calls the first preselected telephone number and gives a status report in machine readable form thereby reporting local conditions and verifying the operability of the call originating function of the device. Second, if the digital inquirer does not request a call back, the device gives a status report in machine readable form on the initial telephone connection. The device also has the capability of giving a synthetic speech status report in response to a telephone inquiry.
It is an object of the present invention to provide a local area monitoring device or system which will communicate alarm reports in either digital or synthetic speech formats depending upon the destination to which the report is directed. It is a further object of the present invention to provide a system which will monitor a selected area while unattended and send reports on conditions at the selected area to a remote location in a form which can be recorded or displayed without the need of an attendant at the remote location.
It is yet another object of the present invention to provide a local area monitoring device which is usable by the hearing impaired.
It is yet another object of the present invention to provide a local area monitoring device which is usable to TTY subscribers.
It is yet another object of the present invention to supply a local area monitoring device which is usable by persons having a computer terminal or personal computer and wishing their computer terminal or personal computer to perform monitoring functions at a local area remote from the computer in an unattended or unsupervised mode.
It is still another object of the present invention to provide a local area monitoring device which is easy to use, easy to install, reliable and inexpensive.
These and other objects and advantages of the present invention will become apparent from the following description taken together with the drawings which will be described in the next section.